JP2004193826A - Speaker cabinet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To notice that a powder material of cellulose such as wood or the like has excellent physical properties as a material for manufacturing a speaker cabinet and to develop a mixed material suitable for the speaker cabinet using synthetic resin and the cellulose powder material so as to provide the speaker cabinet which is inexpensive, small in size, and excellent in acoustic performance and productivity. <P>SOLUTION: The speaker cabinet is made of a mixed material composed of non-chlorine synthetic resin and the cellulose powder ranging from 5 to 500 μm in grain size. The cellulose powder is subjected to surface treatment so as to give an affinity for the synthetic resin. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a speaker cabinet for covering the rear surface of a speaker and increasing acoustic radiation efficiency.
[0002]
[Prior art]
Conventionally, a speaker is attached to a cabinet and used as is well known. Large and high-end speaker cabinets are generally made of wood, but in the case of relatively small ones, synthetic resin is used due to the variety of shapes and the ease of manufacturing by molding means. Alternatively, a synthetic resin or metal molded product mixed with a filler is frequently used. FIG. 1 shows a speaker cabinet of the first embodiment of the present invention as an example of such a small molded speaker cabinet. The cabinet usually has the shape of a housing 1, and is provided on one surface of the housing 1. A speaker mounting hole 13 is formed. One surface on which the mounting holes 13 are formed is commonly called a front plate (or a baffle plate) 12. When the speaker cabinet is small, it is integrally formed with another housing portion 11 of the housing that covers the rear surface of the speaker. Usually, only the front plate 12 is manufactured separately. An input terminal for supplying a signal current from the amplifier (not shown because it is on the rear surface of the housing 1) is provided at an appropriate portion of the speaker cabinet.
[0003]
When the loudspeaker is operated alone, the sound wave radiated forward and the sound wave radiated backward have opposite phases, so that they cancel each other out and the radioactivity is reduced. When the speaker is mounted in the mounting hole 13 of the speaker cabinet, the internal space and the external space of the speaker cabinet are separated from each other by an acoustic circuit such as a diaphragm of a speaker in the case of a closed type or a diaphragm and a port in a case of a bass reflex type. This acoustically cuts off the sound waves before and after the loudspeaker, and improves the radiation efficiency.
[0004]
[Problems to be solved by the invention]
When the speaker cabinet is operated with the speaker attached, the cabinet wall vibrates due to the energy of the sound wave radiated behind the speaker and the vibration energy transmitted from the speaker frame, and is separated from the sound wave radiated directly from the speaker. Emits sound waves. This sound wave is perceived as nonlinear distortion and excessive distortion of the reproduced sound and deteriorates the reproduced sound quality.The frequency component and the level of the intensity of the distorted sound depend on the shape, structure, and material of the cabinet, and in particular, the physical properties of the material, that is, Since physical properties such as density, Young's modulus (rigidity), and tan δ (mechanical internal loss) have a great influence as important factors, how to suppress the cabinet wall vibration is a major issue in speaker cabinet design. Had become.
[0005]
Therefore, in order to solve the above problems from the standpoint of cabinet material, the present invention focuses on a cellulosic powder material such as wood having excellent physical properties as a cabinet material, and from a synthetic resin and a cellulosic powder material to a speaker cabinet. It is an object of the present invention to develop a suitable mixed material and to provide a speaker cabinet which is small in size, has excellent acoustic performance, and has excellent productivity at low cost.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a speaker cabinet of the present invention comprises a mixture of a non-chlorine synthetic resin and a cellulosic powder having a particle size distribution of 5 μm to 500 μm.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The speaker cabinet of the present invention for solving the above problems is manufactured by molding a mixed material of a chlorine-free synthetic resin and a cellulosic powder having a particle size distribution of 5 μm to 500 μm (preferably about 10 μm to 400 μm). Is done. The non-chlorine synthetic resin may be either a thermosetting synthetic resin or a thermoplastic synthetic resin.Examples of the non-chlorine synthetic resin include, for example, polyolefin, polystyrene, and polyester synthetic resins. Among them, polypropylene resin is excellent in terms of mechanical strength, ease of processing, prevention of environmental pollution after disposal, and the like. As the cellulosic powder, a powder of a fibrous material such as wood powder, paper flake, pulp powder, linter powder and the like is used. The purpose of the surface treatment of the cellulose-based powder is to increase the affinity by chemically bonding the surface of the cellulose-based fibrous material to the synthetic resin. The mixing ratio of the cellulose-based powder and the synthetic resin is appropriately about 30% by weight to 70% by weight of the cellulose-based powder in the mixed material. When the mixing ratio of the cellulosic powder is increased, the rigidity is reduced and the brittleness appears, which is unsuitable for some applications.
[0008]
As described above, surface treatment is required for cellulose-based powder. This surface treatment is a means for imparting an affinity between the synthetic resin and the cellulose-based powder. For example, it is effective to esterify a cellulose-based powder substance with a polybasic anhydride such as maleic anhydride. By mixing the esterified cellulose-based powder substance with a synthetic resin and a trace amount of an organic peroxide such as benzoyl peroxide, the affinity between the cellulose-based powder and the synthetic resin is increased, and the mixing ratio of the cellulose-based powder can be increased. Not only does this not only contribute to the above, but also when mixing both materials, even if a large amount of cellulose-based powder is mixed, the fluidity does not decrease, so that its production is easy and the moldability is good. are doing. Also, when the affinity between the cellulose powder and the synthetic resin increases, not only can the mixing ratio be increased, but even if the synthetic resin to be mixed is a polyolefin-based synthetic resin, it paints products and adheres parts. In this case, painting and bonding can be directly performed only by surface treatment by simple mechanical polishing. As a matter of course, it is needless to say that a base treatment such as a plasma irradiation treatment or a primer application further improves the adhesive strength and the stability of the coating film as in the normal case.
[0009]
The chlorine-free synthetic resin mixed with the cellulose powder may be a thermoplastic synthetic resin or a thermosetting synthetic resin. However, a polyolefin-based synthetic resin, particularly a polypropylene resin, is suitable from the viewpoints of ease of molding, basic physical properties of the material, material reuse, waste material treatment, material price and the like. The molding is performed by injection molding, but may be of course extrusion molding. In these molding means, a molding machine for general-purpose resin can be used, and the molding temperature of the mixed material is suitably in the range of about 160 ° C to 200 ° C. In addition, by mixing an appropriate amount of a pigment or a synthetic dye of an appropriate color, a colored cabinet can be obtained without post-processing. Furthermore, for example, wood flour of cypress is used as the cellulosic powder to be mixed, and the scent of wood can be maintained in the product by controlling the molding temperature within the above range. In this case, it goes without saying that the cellulosic powder to be used may be emphasized or mixed with a synthetic flavor.
[0010]
In the speaker cabinet of the present invention described above, since the affinity for the molecules of the synthetic resin is increased by the surface treatment of the mixed cellulosic powder, the speaker cabinet can be mixed at a relatively large ratio with the synthetic resin. it can. In addition, when the ratio of the cellulosic powder is large, the rigidity of the product is high, and when the wall of the cabinet is bent, such as when the wall of the cabinet vibrates, the mechanical internal loss of the cellulosic powder itself (commonly referred to as “bending deformation”). Indicates that the mechanical internal loss of the synthetic resin mixed with tan δ) works effectively, resulting in a large mechanical internal loss as a whole. The above-mentioned increase in rigidity of the wall body and increase in mechanical internal loss are caused by the fact that when the speaker is mounted on the speaker cabinet and operated, resonance of the wall hardly occurs, and a large amplitude is temporarily generated by a pulse signal. Even if the wall vibration occurs, it disappears in a short time, and the adverse effect on the deterioration of the reproduced sound is small.
[0011]
In addition, the fluidity of the mixed material is extremely good due to the increase in the affinity between the above-mentioned cellulose powder and the molecule of the synthetic resin, and even when injection molding is used as a molding means, a molding machine for a general-purpose resin can be used. There is no extra cost for capital investment, and there is no difficulty in production because the molding conditions are the same as usual. Also, since the fluidity is maintained even if the mixing ratio is large, the production efficiency does not decrease, and the cylinder or screw of the mold or the molding machine is compared with the case where other inorganic fillers are used. The maintenance cost of the equipment can be kept low since the wear of the equipment is small.
[0012]
Regarding the product of the present invention, the mixed material constituting the housing can be reused, and since it uses a non-chlorine synthetic resin, it can be incinerated even when discarded. Since there is little residual ash, there is little environmental pollution.
[0013]
【Example】
FIG. 1 is a perspective view showing the appearance of the speaker cabinet of the first embodiment. The cabinet usually has the shape of the housing 1 and includes a housing portion 11 and a front plate 12 formed separately. The housing portion 11 and the front plate 12 are connected to the housing 1 by tapping screws, and a closed box is provided. To form The front plate 12 has a speaker mounting hole 13 formed therein. Although not shown, an input terminal for supplying a signal current is provided on the back of the speaker cabinet, and a lead wire 14 connected to the speaker is connected to the input terminal in advance. Further, a reinforcing rib 15 is formed on the inner surface of the cabinet.
[0014]
The configuration of the speaker cabinet of the first embodiment is as follows: 1) polypropylene resin is used as a non-chlorine synthetic resin; and 2) 100 parts by weight of wood powder having an average particle size of 100 μm is 10 parts by weight of maleic anhydride. 3) Using benzoyl veloxide as the organic oxide, 49.5% by weight of the polypropylene resin, 50% by weight of the treated wood powder, and 0.1% of benzoyl veloxide. 5% by weight is mixed to prepare a mixed material for molding. 4) Next, the mixed material is molded at a set resin temperature of 160 ° C. to 200 ° C., and the speaker cabinet of the first embodiment shown in FIG. Got. The dimensions of the first embodiment are as follows: length × width × depth is 170 mm × 170 mm × 120 mm, the thickness of the cabinet wall plate is about 4 mm, and the density of the cabinet wall plate is 1.10 gr / c. c.
[0015]
FIG. 2A shows an analysis result of excessive vibration of a cabinet wall plate when a pulse signal is applied by attaching a speaker having a diameter of 12 cm to the speaker cabinet. For comparison, FIG. 2B shows an excessive vibration analysis of a cabinet wall plate of a speaker cabinet (cabinet wall plate thickness: 4 mm, density: 0.9 gr / cc) having substantially the same outer dimensions and a polypropylene resin alone for comparison. The results are shown in FIG. 3 (c), although the material is different from the synthetic resin, but for reference, the thickness is 9 mm and the density is 0.69 gr / c. c shows the results of the analysis of the excessive vibration of the cabinet wall plate of the speaker cabinet using the MDF wood board (medium density wood fiber board). The vertical axis of the transient vibration characteristic diagram is the output voltage of the vibration pickup. According to the analysis result, the first embodiment shows that the peak output voltage is higher than that of the cabinet made of polypropylene resin alone shown in the characteristic diagram (b). Is as low as about 0.67 times (−3.48 dB). If the vibration level of the cabinet wall plate is as low as this, the difference can be sufficiently detected, and the effect of reducing distortion with respect to the reproduced sound of the speaker cabinet of the first embodiment is apparent.
[0016]
FIG. 3A shows the temperature characteristics of the Young's modulus E 'of the constituent material of the first embodiment by a solid line. The measurement temperature range is in a range of 0 ° C. to 50 ° C. in consideration of a practical use state. For comparison, (b) in the same figure shows the temperature characteristic of the Young's modulus E ′ of the speaker cabinet made of a polypropylene resin alone by a dashed line.
[0017]
4 (a) and 4 (b) show the temperature characteristics of the tan δ value of the speaker cabinet of the first embodiment and the polypropylene resin alone by a solid line and a dashed line, respectively. From the temperature characteristic diagrams of the Young's modulus and tan δ, the cabinet of the first embodiment has a small change in the rigidity of the cabinet and the mechanical internal loss even when the temperature of the outside air changes, and therefore, it decreases even when the outside air temperature increases. In other words, in other words, there is a feature that the influence of the cabinet vibration on the reproduced sound hardly changes depending on the season.
[0018]
Although the embodiments and the modified examples considered to be representative of the present invention have been described above, the present invention is not necessarily limited to the structure of these embodiments, and the material is changed and used, and Equipped with the above-mentioned constitutional requirements of the present invention, such as modification of a molding means including a heating means, and achieves the object of the present invention, and can be appropriately modified and implemented within a range having the following effects. Things.
[0019]
【The invention's effect】
As described above, the speaker cabinet of the present invention has a high affinity for synthetic resin molecules due to the action of the esterification surface treatment of the cellulose-based powder. Has high rigidity and exhibits large mechanical internal loss. The above-described increase in rigidity of the cabinet wall and increase in mechanical internal loss are caused by the fact that when a speaker is mounted on the speaker cabinet and operated, resonance of the wall hardly occurs, and the pulse is temporarily generated by a pulse signal. Even if the wall vibration is generated, it disappears in a short time, and has an effect that the adverse effect on the deterioration of the reproduced sound is small.
[0020]
In addition, the fluidity of the mixed material is extremely good due to the increase in the affinity between the cellulose powder and the molecules of the synthetic resin, and a molding machine for a general-purpose resin can be used at the time of injection molding. Not only does it take place, but also the molding conditions remain the same, so there is no problem with production. Also, even if the mixing ratio is large, the fluidity is maintained, so that the production efficiency does not decrease, and furthermore, the wear of the cylinders and screws of the mold and the molding machine can be reduced, so that the maintenance cost of the equipment is other. It also has the effect that it can be kept low compared to the case where an inorganic filler is used.
[0021]
Further, with respect to the product of the present invention, the mixed material constituting the housing can be reused, and when discarded, it can be incinerated because it is mainly made of non-chlorine synthetic resin. This has a remarkable effect that cannot be expected from the conventional one, which is less likely to cause environmental pollution due to less residual ash.
[Brief description of the drawings]
FIG. 1 is a perspective view of a speaker cabinet according to a first embodiment.
FIG. 2 is a transient vibration characteristic diagram showing a transient vibration analysis result of the cabinet wall plate.
FIG. 3 is a temperature characteristic diagram showing a temperature change of the Young's modulus of the cabinet wall plate material.
FIG. 4 is a temperature characteristic diagram showing a temperature change of tan δ of the cabinet wall plate material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing of speaker cabinet 11 Housing part 12 Front plate 13 Speaker mounting hole 14 Lead wire 15 Reinforcement rib

Claims (8)

A speaker cabinet made of a mixed material of a chlorine-free synthetic resin and a cellulosic powder having a particle size distribution of 5 μm to 500 μm. The speaker cabinet according to claim 1, wherein a mixing ratio of the cellulose-based powder in the mixed material is 30% by weight to 70% by weight. The speaker cabinet according to claim 1, wherein the non-chlorine-based synthetic resin is a polyolefin-based synthetic resin, a polyester-based synthetic resin, or a polystyrene-based synthetic resin. The speaker cabinet according to any one of claims 1 to 3, wherein the cellulosic powder is a cellulosic powder that has been subjected to a surface treatment for imparting an affinity to a non-chlorine synthetic resin. The speaker cabinet according to any one of claims 1 to 4, wherein the mixed material is colored by a coloring material. 5. The speaker cabinet according to claim 1, wherein the cellulosic powder is a substance having an inherent fragrance, and is molded at a temperature range of 160 ° C. to 200 ° C. at the time of molding. The speaker cabinet according to any one of claims 1 to 6, wherein the surface treatment for imparting an affinity to the non-chlorine-based synthetic resin to the cellulose powder is an esterification treatment with a polybasic acid anhydride. The speaker cabinet according to any one of claims 1 to 7, comprising a mixed material of a chlorine-free synthetic resin, the esterified cellulose-based powder, and an organic peroxide.

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